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A Novel System for the Measurement of Dynamic Loading on a Bicycle FrameConsell, Ryan January 2013 (has links)
The design of bicycle frames has remained fairly static for the majority of the past century, but recent increases in demand for high performance bicycles has created an accelerated design cycle that requires innovation. In order to design new frames with confidence in their capacity to withstand the rigors of use, reliable data about the nature of that use is needed, but this data is not currently available. The purpose of this research was to develop and implement a system that is capable of interpolating loads applied to a bicycle frame during vigorous riding for the purpose of improving the quality of information available to bicycle designers.
The system that was developed employed finite element modeling to locate strain gauges on a frame and a least-squares approximate solution of strain readings to interpolate the applied loads. At its best, the system is capable of resolving loads with better than a 2% error. This system is limited, though, as it can only be applied in cases where the frame has a significant strain reaction to a load case but does not have a significant change in geometry during loading. This system was implemented on a cross-country mountain bicycle frame for the purposes of determining a rider weight to load relationship and to compare the standardized test procedures for bicycles to the loads experienced in the field.
It was confirmed that there is a linear relationship between rider weight and load on the frame for all component forces except that applied to the bottom bracket, out of plane with the bicycle frame. It was also found that the British Standards fatigue testing practices, which are used internationally to assess bicycle safety, are inconsistent in their representation of realistic riding conditions when compared with the results from the field tests. Some loads appear conservative, some offer a very large factor of safety, and two are not represented at all. In particular, the moment about the bottom bracket due to pedaling and the load on the seat from the rider appear to consistently exceed the standardized test requirements while the moment caused by fork splay seems much smaller than the tests demand.
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Modeling the effect of activelayer deepening on stocks ofsoil organic carbon in thePechora River BasinEriksson, Pia January 2012 (has links)
This study investigates how the estimated thickening of the active layer will affectthe soil organic carbon in permafrost soils. The focus lies on estimating how muchof the upper permafrost soil organic carbon will be affected by the active layerdeepening due to global warming, on what timescale the deepening will take placeand if the estimated changes differ depending on the extent of permafrost in theregion. A model made in a Geographic Information System (GIS) combines datasetsfrom The Northern Circumpolar Soil Carbon Database, field data of soil organiccarbon content (SOCC) in different permafrost soil horizons in the Usa basin anddata of recent and future active layer depth from a spatially distributed permafrostdynamics model in the Pechora River Basin. The model shows that in 1980, 75% ofthe available 0–100 cm Gelisol soil organic carbon mass (SOCM) has affected byseasonal thawing. In 2050 the proportion is increased to 86% and by 2090 almostthe whole study area has an active layer deeper than 1 meter (98%). This indicatesan increase from approximately 0.64% to 0.84% of the total 1–100 cm SOCM in thenorthern permafrost region. The change is more gradual in the isolated and thesporadic permafrost zones and more abrupt in the continuous and discontinuous regions.
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Urban Pathways: Redesigning Toronto's MobilityLiefl, Jessica Elizabeth January 2011 (has links)
As an increasing proportion of the world’s population travels ever-longer distances between their home and place of work, urban mobility networks have had to cope with this dramatic increase in movement. These networks not only occupy escalating amounts of undeveloped land, but also work to re-shape the public spaces and landscapes of the urban realm. The City of Toronto’s mobility (or increasing lack thereof) has an enormous influence on its culture and urban development; the car and its attendant infrastructures heavily govern the city’s growth by supporting urban sprawl. In order to redevelop public space, equalize access to mobility, and improve the way we move through the city, a new system of infrastructure is required; one that can negotiate through an asphalt-dominated landscape while creating a sustainable transport alternative.
This thesis proposes new mobility networks as strategies of intensification through a repositioning of the bicycle and by prioritizing its supporting infrastructure along existing underutilized service lands in the City of Toronto. By further developing both the rail and hydro corridors as a city-wide network of mobility paths, and eventually phasing them into a series of linear parkways, distant parts of the city would become accessible for long-haul trips. The second design component is a series of bicycle hubs located at, and tailored to, strategic locations throughout the city’s existing corridors and transit lines. These new civic amenities have the potential to enrich urban placemaking, while acting as social centres that anchor newly connected communities.
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An Analysis of Stated and Revealed Preference Cycling Behaviour: A Case Study of the Regional Municipality of WaterlooRewa, Kyrylo Cyril January 2012 (has links)
Amongst transportation professionals there is a motivation to increase the use of active transportation to achieve contemporary transportation engineering goals. This research describes a year-long GPS cycling study conducted in partnership by the University of Waterloo and the Region of Waterloo Ontario. Data were collected from 415 self-selected cyclists, using two distinct data collection mechanisms. Data collected from GPS units revealed trip origins, destinations, and routes; the data also contain time stamps from which travel speeds can be computed. An online survey was administered to gather cyclists’ socio-economic information and household composition. The survey also collected responses to questions regarding preferences for cycling infrastructure and overall satisfaction.
The trip data allow for several important conclusions. The average trip length observed in the study was 6.96 kilometers; utilitarian trips (i.e. non-recreational) constitute 92% of the observed trips. This suggests that cyclists are able to complete daily activities – commuting, shopping, etc. – with less overall travel than the general population. The trip data also suggests relationships between the propensity to cycle and land use patterns. Strong positive correlations are demonstrated between higher land use density and the number of cycling trips; moreover, cycling trips tend to be more direct in areas with traditional neighbourhood design. The time at which the trips were taken – predominantly the am or pm peaks – suggest that the cyclists’ mode choice results in lowering peak demand and, therefore, reducing regional congestion. Fewer and typically shorter cycling trips were observed during winter months, presumably as a result of less favorable climate.
Participants in the study are typically higher-than-average earners and mirror the overall regional age distribution, although seniors and children were underrepresented. The cyclists in the study are predominantly male which may reflect an overall higher propensity to cycle amongst men compared to women. Cyclists’ households are more likely than the general population to own fewer cars than licensed drivers which may be interpreted as a cost saving opportunities for these households. Finally, the survey data suggests that the single largest impediment to increased cycling is a perception of poor safety for cyclists, particularly in terms of interactions with automobiles.
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Styrketräning en gång per vecka förbättrade anaerob kapacitet hos cyklister och triathleter : En 12 veckor lång interventionsstudie / Strength training once a week improved anaerobe capacity in cyclists and triathletes : An 12 week long intervention studyAlmström, Jennie, Gustavsson, Simon January 2012 (has links)
Triathleter och cyklister är uthållighetsidrottare med extrem träningsvolym och stort krav på aerob kapacitet, dock krävs även anaerob- power och muskelstyrka för delmoment som backar och tempoväxlingar. Många uthållighetsidrottare tvekar över att implementera styrketräning i tron att effekten ska påverka deras prestation negativt, dessutom gör den höga träningsvolymen det svårt att kombinera. Styrketräning som komplement till uthållighetsträning har dock visats ge positiv effekt och kan förslagsvis förbättra prestation. Syftet var att undersöka huruvida ett styrketräningspass per vecka kan förbättra anaerob kapacitet hos cyklister och triathleter samt om en eventuellt ökad benstyrka kan påverka simtiden hos triathleter. Metoden var en interventionsstudie med pre- och posttest där deltagarna fick genomföra ett styrketräningspass innehållandes tre övningar, en gång per vecka under 12 veckors tid, som komplement till ordinarie träning. Resultatet vid test av maximal styrka i benpressmaskin påvisade en signifikant ökad benstyrka för interventionsgruppen med p = 0,001, en styrkeförbättring på 16,5 %. Wingate- testet visade signifikant förbättring för maxeffekt, p = 0,003, en förbättring med 11,1 % samt maxeffekt per kilo kroppsvikt, p = 0,001, en förbättring på 11,9 %. För kontrollgruppen sågs inga noterbara förändringar och inget samband kunde heller ses mellan en ökad benstyrka och simprestation.Vår styrketräning i kombination med deras ordinarie träning kan förslagsvis fungera synergiskt och optimera prestationen. / Triathletes and cyclists are endurance athletes with extreme training volume and high demands on aerobic capacity but the sport also requires anaerobic power and muscular strength for example hills or changes in tempo. Many endurance athletes do hesitate to implement strength training with the belief that the effect will negatively affect their performance, the high training volume also makes it difficult to combine. Strength training as a complement to endurance exercise has been shown to have a positive effect and may improve performance. The aim was to investigate whether strength training once a week can improve anaerobic capacity among cyclists and triathletes, and if any potential increase in strength capacity may affect swim performance in triathletes. The method was an interventional study with pre and post-test in which participants had to conduct a workout consisting of the three exercises, once a week for 12 weeks, in addition to regular exercise. The results from the test of maximum strength in the leg press showed a significantly increased strength in the intervention group, p = 0.001, a strength improvement of 16.5%. The Wingate test showed a significant improvement in maximum power, p = 0.003, an improvement of 11.1%, and the maximum power per kilogram bodyweight, p = 0.001, an improvement of 11.9 %. For the control group, there were no noticeable changes and no association was seen between increased strength and swim performance. Our strength training in combination with the regular workout can probably work synergistically and optimize their performance.
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The Study of Thermo-mechanical Behavior of PBGA Package's InterfaceChen, Yung-Chang 16 October 2003 (has links)
The Plastic Ball Grid Array (PBGA) package and flip-chip technology have been widely used in the microelectronics industry. However, due to the effect of hygroscopic and thermal stresses, the reliability is still of concern during manufacturing and operation, especially for the thermal-mechanical behavior of its corresponding interfaces. Influences of the storage conditions and reflow parameters on the warpage of the PBGA package are investigated in this study first. As the results, the warpage reflected the interaction of the extent of moisture absorption and the change in reflow parameters significantly. Furthermore, a critical relative moisture absorption between 0.25% and 0.30% is found for a considerable warpage response. Next, this study presents an experimental investigation of the adhesion strength of epoxy-based encapsulant material to solder mask coated FR-4 substrate under thermal cycling. Effects of the number of thermal cycles on the interfacial strength are investigated by using button shear test. The relationship between the interfacial strength and thickness of solder mask is also examined. Moreover, to characterize the degradation and fracture behavior, the morphologies of fractured surfaces of the test specimens are analyzed by scanning electron microscopy. The results of this experiment show that the interfacial strength of the epoxy-based encapsulant/solder mask/substrate joint is apparently reduced by thermal fatigue. And, the test specimen with larger solder mask thickness has higher interfacial strength. Finally, the single-lap joint test, nonlinear finite element analysis and Moiré interferometry are employed to obtain strain/stress distributions on the interface of solder mask and substrate. The effects of solder mask thickness and overlap length are then determined, separately. The results of this study can afford important information for characterizing the features of moisture absorption, warpage and interfacial adhesion of PBGA packages. Furthermore, it can be helpful to identify improvements required in reliability of the package design.
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The Effect of Temperature Range Variation on Flip-Chip Package under Temperature Cycling TestChen, Tsung-Hui 15 August 2004 (has links)
Abstract
Accompany a rapid growth in the semiconductor industry in the past few year, most components gradually used the small dimension as its basic structures. Due to the reduction of component size will induces highly concentrated on circuit and dimension, it also incurs a lots problem, such as electromagnetic interference, high temperature and thermal stress, which will decrease the product reliability. The most common damage in the semiconductor product is thermal fatigue, which is caused by thermal stress concentrated under repeatedly temperature variation loading. Usually, the thermal cycle loading is applied to induce the fatigue destruction and predict the product reliability, but this method spends one cycle for 80min which is time-consumption. Therefore, in this thesis, the finite element method package is used to simulate and evaluate the plastic variation of solder bump and the relation between different temperatures loading and equivalent plastic strain under different temperature range test. Through the Coffin-Manson equation, the equivalent plastic strain can be used to predict the fatigue live, which can be precisely accelerating the fatigue test.
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The Study on the Stress and Fatigue Life in Ferrule-Epoxy-Fiber Module of Optical Fiber Connector under Thermal CyclingLin, Chi-Chau 28 July 2003 (has links)
The effects of different ferrule length and epoxy layer thickness of the module of optical fiber connector under thermal cycling are investigated in this thesis. The finite element method package, MSC. MARC, is used in this study and the coupled thermal-elastic-plastic model is employed in the analysis. The mechanical behavior and life prediction with different length of ferrule and thickness of epoxy layer are considered. It is shown that the thickness of epoxy layer has the major effect on the life of the module. The stress and strain in the fiber and epoxy layer are decreasing with increasing of ferrule length, and the life of the module is increasing with increasing of thickness of epoxy layer. Finally, we recommend the ferrule length can be designed between 7.89mm ~10.5mm.
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Effects of Neo40TM with caffeine on cycling time trial performanceLee, Joowon 29 October 2013 (has links)
The vasodilatory effects of nitric oxide (NO) have attracted a lot of attention from many investigators who are interested in treatment for cardiovascular disease or hypertension. Recently, however, NO has drawn the attention of people who are looking for new avenues to improve their health, as well as effective ways to enhance exercise performance. In particular, NO, a potent vasodilator, is known to regulate blood flow to active muscles and improve muscle contractile efficiency during exercise, allowing participants to exercise much longer with less fatigue. Neo40TM contains 420mg of a nitric oxide blend with 75mg of caffeine. Therefore, the purpose of the current study was to investigate the effects of Neo40TM on cycling time trial performance and exercise efficiency in 15 moderately trained cyclists. The protocol was a double-blind, randomized, placebo-controlled, two-period, within-subjects crossover study. The treatments were Neo40TM, and a non-caloric similarly favored placebo (PLA). Fifteen participants were randomly assigned to ingest a Neo40 TM or PLA in lozenge form. Exercise performance was assessed by time to complete a simulated 20.15km time-trial course. Exercise efficiency was also measured by VO2 and lactate accumulation at standardized submaximal steady-state exercise intensities. Time-trial performance was enhanced by 2.1% when participants consumed Neo40TM compared to a PLA without a significant difference in rating of perceived exertion (RPE). Time to complete 6km, 10km, 19.5km and 20.15km of cycling was analyzed by gender. A significant difference was found in female subjects at all time points, but not in male subjects. We did not find significant treatment effects for VO2, respiratory exchange ratio (RER), RPE, heart rate (HR) and lactate concentration during steady state exercise. In conclusion, acute supplementation with Neo40TM improved time-trial performance by an average of 2.1% although there were no treatment effects in regards to factors related to work efficiency. / text
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Changes in muscle activity and kinematics of highly trained cyclists during fatigueJoubert, Jason E.G. 03 August 2015 (has links)
Up to 85% of cyclists experience repetitive strain injuries (RSI's). During long bouts of repetitive tasks, muscle fatigue may cause mal-alignments in kinematics, having cumulative effects, leading to an RSI. Purpose: The study's purpose was to examine how changes in localized muscle fatigue relate to changes in movement kinematics in highly trained cyclists throughout a full fatigue protocol. Methods: Seven highly trained cyclists participated in a 2 session experiment. Session 1 included a VO2 max test and familiarization trial and Session 2 was the fatigue protocol. Kinematic angles measured were trunk lean, hip, knee, ankle, and knee splay angle. Mean angle (MA) and range of motion (ROM) was calculated for each revolution thought the trial. Muscles monitored were the quadriceps, hamstring, gastrocnemius, and tibialis anterior. EMG median frequency (MDF) for each muscle was calculated for each revolution by averaging MDF for the two halves of each revolution. Cross-correlation analysis was done on MDF and MA data and MDF and ROM data. Results: All subjects exhibited increases in trunk lean and decreases in ankle angle. Non-monotonic changes were observed in trunk lean, ankle, knee splay angle, and among ROM results for all 5 angles. A 1-tailed T-tests for all subjects, revealed that HAM (p = 0.020) and GAS (p = 0.018) exhibited significant muscle fatigue. One-tailed T-tests yielded significantly negative cross-correlation time lags [Greek small letter tau] for trunk lean MA, ROM, and hip MA. Conclusions: Non-monotonic changes are present in kinematics and MDF. Therefore pre vs. post experimental designs cannot quantify fatigue processes. Shifts in trunk lean MA, ROM and hip MA are significantly correlated with preceding decreasing shifts of MDF (indicative of onset of fatigue). / text
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